Antenna system



March 11, 1941. USSELMAN 2,234,293

ANTENNA SYSTEM Filed Sept. 19, 1939 TRANSMITTER INVENTOR. GEORGE USSELMAN BY 70 mAA/s- I M/TTER A 7 WW ATTORNEY.

Patented Mar. 11', 1941 UNITED STATES 2,234,293 ANTENNA SYSTEM George Lindley Usselman, Rocky Point, N.

Y., as-

signor to Radio Co poration of America, a corporation of Delaware Application September 19, 1939, Serial No. 295,566

19 Claims.

The present invention relates to short wave antennas and, more particularly, to directive short wave antenna arrays.

An object of the present invention is the pro- 6 vision of a short wave antenna array which will be mechanically simple and structurally rugged.

Another object is the provision of a novel means for energizing a short wave antenna array.

Still another object is the provision of simple rugged supporting structure for short wave antenna array.

A further object is the provision of a novel means for coupling a source of highfrequency oscillation s to utilization apparatus.

Still a further object is the provision of an antenna and reflector array which is entirely grounded against lightning strokes, as well as being mechanically sturdy.

The foregoing objects, and other objects which may appear from the following detailed description, are obtained by mounting dipole radiators along the edges of a longitudinalslit in a split tubular conductor. The split tubular conductor is so dimensioned as to form a tuned circuit resonant at the operating frequency of the antenna system. The slit along the length of the tube and the radiators constitutes the capacity and the inner circumferential length of the wall of the tube and. the radiators constitutes the inductance of the tuned circuit. A similar form of construction is utilized for the reflector array, if one is desired.

A more complete understanding of the present invention will be had by reference to the following detailed description which is accompanied by a drawing in which Figure 1 shows in perspective one form of the present invention, while Figure 2 is a cross-sectional view thereof; Figure 3 illustrates a modification of the invention while Figure 4 illustrates the manner of supporting and energizing a reflector array for an antenna such as shown in either Figures 1, 2 or 3.

Referring, now, to Figure 1, I have shown a 5 tubular conductor I 1] having flanges II and 12 along the edge of the longitudinal slit IS in the tube. On these flanges I l and I2 are mounted dipole radiating members I, 2, 3, 4, 5, 6, l and 8. The radiating members are arranged in pairs set at any desirable spacing and may be of any desired length as determined by the operating frequency. The flanges H and [2 may be integral portions of tube Ill, bent to the desired position, or they may be comprised of separate metal pieces brazed or welded along the edges of the slit to give a desired shape. The shape is shown clearly in the cross-sectional view of Figure 2.

The antenna of my invention may be energized by a transmission line from a source G connected as shown in Figure 1 to one end of the tubular 5 conductor, or the transmission line may be brought in through apertures at the back of the tube at a more nearly central location as indicated in Figure 2. The points of connection 'of the conductors of the transmission line to member ll! should preferably be symmetrically disposed with respect to slit l3. The feed impedance of the antenna may be adjusted to the impedance of the transmission line or generator by varying the spacing between the points of connection. In operation, the split tubular conductor Hi forms a tuned circuit. The slit H3 or space between the flanges H and I2, together with the radiators, constitutes a capacity and the interior circumferential length of the wall of the tube, together with the radiators, constitutes the inductance. This distance is indicated by reference letter 03 in Figure 2. The length d and the capacity of slit l3 are so proportioned that electrical resonance occurs at the operating frequency of an antenna. The greatest oscillating current occurs at the back wall of the tube at 2i in Figure 2 and the highest oscillating potential exists between flanges l i and i2 and the radiators attached thereto. The high frequency oscillating potential between flanges I l and I2 produces high frequency oscillating currents in the individual radiators I to 8 so that they radiate in an in-phase relationship as usually provided in broadside antenna arrays, The tube l 0 may be mounted horizontally so as to hold the radiators in a vertical position, as shown in Figures 1 and 2, or it may be mounted for vertically polarized radiation to hold the radiators in a horizontal position, as shown in Figure 3, if horizontally polarized waves are desired.

If it is desired to mount the radiators in a horizontal position with the tubular member l0 vertical the split conductor may be made to serve as a mast and transmission line, as well as part of the antenna. The lower end of the split tubular conductor may be fastened to a post 30 (Figure 3) by means of straps 3| and 32 bolted to the back of the tubular conductor. If desired, a flange 33 may be brazed or welded to the tubular conductor for convenience in attaching the straps. If the post 30 is not conducting it is desirable to ground the tubular conductor II) as a protection against lightning by means of a grounded wire connected to straps 3i, 3! or flange 33.

; 2,1 and 8 back a l of the split'tube.

In Figure 3' a portion of the nearer side of the In each of the embodiments described above along the flanges ll to give the optimum the spacing of the radiators and I2 may be varied so as results. In some circumstances, better results may be obtained by setting the end radiators I, short distance from the ends The directivity of the antenna may be controlled by changing the phase of the A convenient manner of varying the phase relationship is by varying the capacity of the gap l3 between flanges H and I2. A narrowing of the gap l3 or widening of the flanges II and I2 increases the capacity at that point above the average and, therefore, causes the current to'lag in phase at that point; whereas, a decrease in capacity at some other point below the average causes the current to load in phase. The tendency is for all points along the split tubular conductor Hi to have the same phase relations if the structure is entirely symmetrical. However, the end effect of the split tube l0. undoubtedly changes the phase relationship near the ends. For this reason, the radiating members I, 2, 1 and 8 should not be mounted too near the ends of the tube; if they are mounted comparatively close to the ends then the gap I3 will have to be varied to compensate for this end effect.

The modification of my invention shown in Figure 4 comprises two antenna arrays mounted on a pole to form a directive system with'only one direction of maximum response. Each of the antenna arrays is substantially alike and substantially as described with reference to Figure 1. The split tubes l0, ID are mounted par-- allel to each other and all the radiators on the flanges H and I2 are alsomounted parallel to eachother. Either of the sets of radiators, may be considered the reflector and the other as the antenna, depending upon the exact phase and manner of energization. .Tl'ie antennas are energized in parallel except that in the figure the lines to the right hand antenna are provided with phasing loops 4.: and 46 for adjusting the phase of the current in this array for the desired direction and directivity of the beam. The dis-- tance S between the radiators of the array, as well as the length L of theradiators, has an important effect on the horizontal and vertical directivity and must be-considered in adjusting the dimensions of loops 45 and, 46. A' convenient manner at mounting the directive system on the top ofp'ole 30 is to fasten the tubes l0, In to a flat metallic plate 44 by means of flanges 43. If

desired, of course, the radiator system of Figure 4 may be mounted vertically as described with reference to Figure 3.

While I have particularly shown and described several modifications of my invention, it is to be clearly understood thatfmy invention is not limited thereto but that modifications within v the scope of the invention'may be made.

I claim:

1. Means for coupling a dipole antenna array to a transmission line comprising anelectrically conducting tubular member extending the length way of connecting the of said array and forming a'substantially closed channel for the transmission of electromagnetic flux from one end to the other, the transverse dimensions of said member being so proportioned that resonance occurs at the operating frequency of said antenna array, said dipoles being coupled to said member at points of maximum oscillating potential.

2. Means for coupling a dipole antenna array to a transmission line comprising an electrically conducting tubular member extending the length of said array and having a longitudinal slit along the length thereof, the capacity between the edges of said slit being so related to the inductance 'of the circumferential conducting path of said member that said path is resonant at the operating frequency of said array and means for coupling the antennae of said array to the edges of said slit.

3. Means for coupling ,a dipole antenna array to a transmission line comprising an electrically conducting tubular member extending the length of said array and having a longitudinal slit along the length thereof, conducting flanges along the edges of said slit, the capacity between said flanges being so related to the inductance of the interior circumferential conducting path of said member that said path is resonant at the operating frequency of said array and means for coupling the antennae of said array to said flanges.

4. A directional antenna array comprising a horizontal longitudinal conducting tubular member extending the length of said array, said member having a longitudinal slit along the length thereof, the capacity between the edges of said slit being so related to the inductance of the interior circumferential conducting path of said member that resonance occurs at the operating frequency of said array, vertical radiating members connected to the edges of said slit and a transmission line connected to said tubular member.

5.,A directional antenna array comprising a horizontal longitudinal conducting tubular member extending the length of said array, said member having a longitudinal slit along the length thereof, the capacity between the edges of said slit being so related to the inductance of the interior circumferential conducting path of said member that resonance occurs at the operating bers connected to the edges of said slit and a transmission line connected to said tubular member at symmetrical points with respect to said slit.

6. A directional antenna array comprising a vertical electrical conducting tubular member, said member having a longitudinal slit along the length thereof, the capacity between the edges of said slit beingso related to the inductance of the interior circumferential .conducting path of said member that resonance occurs at the operating frequency of said array, horizontal radiating members connected to the edges of said slit and a transmission line connected to said tubular member; 1

7. A directional antenna array comprising an electrically conducting tubular member, said member having a longitudinal slit along the of said slit being so related to the inductance of frequency of said array, vertical radiating memlength thereof, the capacity between the edges the interior circumferential conducting path of I said member that resonance occurs at the operating frequency of said array, radiating members connected to the edges of said slit and a transmission line connected to said tubular member.

8. A directional antenna array comprising a vertical electrically conducting tubular member, said member having a longitudinal slit along the length thereof, the capacity between the edges of said slit being 50 related to the inductance of the circumferential conducting path of said member that resonance occurs at the operating fre-' quency of said array, horizontal radiating members connected to the edges of said slit and a transmission line connected to said tubular member at symmetrical points with respect to said slit.

9. A directional antenna array comprising a horizontal electrically conducting tubular member extending the length of said array, said member having a longitudinal slit along the length thereof, parallel conducting flanges along the edges of said slit, the capacity between said flanges being so related to the inductance of the circumferential conducting path and said member that resonance occurs at the operating frequency of said array, vertical radiating members connected to said flanges and arranged in a plane perpendicular to said flanges and a transmission line connected to said tubular member.

10. A directional antenna array comprising an electrically conducting tubular member extending the length of said array, said member having a longitudinal slit along the length thereof, parallel conducting flanges along the edges of .said slit, the capacity between said flanges being so related to the inductance of the circumferential conducting path and said member that resonance occurs at the operating frequency of said array, radiating members connected to said flanges and arranged in a plane perpendicular to said flanges and a transmission line connected to said tubular member.

11. directional antenna array comprising a horizontal electrically conducting tubular member extending the length of said array, said member having a longitudinal slit along the length thereof, parallel conducting flanges along the edges of said slit, the capacity between said flanges being so related to the inductance of the interior circumferential conducting path and said member that resonance occurs at the operating frequency of said array, vertical radiating members connected to said flanges and a transmission line connected to said tubular member at symmetrical points with respect to said slit.

12. A directional antenna array comprising a vertical electrically conducting tubular member, said member having a longitudinal slit along the length thereof, parallel conducting flanges along the edges of said slit, the capacity between said flanges being so related to the inductance of the circumferential conducting path of said member that resonance occurs at the operating frequency of said array, horizontal radiating members connected to said flanges and a transmission line connected to said tubular member.

13. A directional antenna array comprising a vertical electrically conducting tubular member, said member having a longitudinal slit along the length thereof, parallel conducting flanges along the edges of said slit, the capacity between said flanges being so related to the inductance of the circumferential conducting path of said member that resonance occurs at the operating frequency of said array, radiating members connected tosaid flanges and perpendicular thereto and a transmission line connected to said tubular member at symmetrical points with respect to said slit.

14. A directional antenna array comprising an electrically conducting tubular member, said member having a longitudinal slit along the length thereof, parallel conducting flanges along the edges of said slit, the capacity between said flanges being so related to the inductance of the circumferential conducting path of said member that resonance occurs at the operating frequency of said array, radiating members connected to said flanges and perpendicular thereto and a transmission line connected to said tubular member at symmetrical points withrespect to said slit.

15. A directional antenna array comprising a plurality of horizontal electrically conducting tubular members extending the length of said array in a parallel relationship, said members each having a longitudinal slit along the length thereof, the capacity between the edges of said slits being so related to the inductance of the circumferential conducting path of each of said members that resonance occurs at the operating frequency of said array, vertical radiating members connected to the edges of the slits along each of said members, a transmission line connected to each of said tubular members at symmetrical points with respect to the slits in said members and means for adjusting the relative phase of energy supplied to said tubular members.

16. A directional antenna array comprising a plurality of horizontal longitudinal conducting tubular members extending the length of said array in a parallel relationship, said members each having a longitudinal slit along the length thereof, parallel conducting flanges along the edges of each of said slits, the capacity between each pair of said flanges being so related to the inductance of the circumferential conducting path of each of said members that resonance occurs at the operating frequency of said array;

vertical radiating members connected to each of said flanges and in a plane perpendicular to said flanges, a transmission line connected to each of said tubular members at symmetrical points with respect to said slits and means for. adjusting the relative phase of energy supplied to said tubular members by said transmission line.

17. A directional antenna array comprising a plurality of longitudinal conducting tubular members extending the length of said array in a parallel relationship, said members each having a longitudinal slit along the length thereof, parallel conducting flanges along the edges of each of said slits, the capacity between each pair of said flanges being so related to the inductance of the circumferential conducting path of each of said members that resonance occurs at the operating frequency of said array, radiating members connected to each of said flanges, and in a plane perpendicular to said flanges, a transmission line connected to each of said tubular members at symmetrical points with respect to said slits and means for adjusting the relative phase of energy supplied to said tubular members by said transmission line.

18. Means for coupling an antenna to a transsaid antenna being connected to the edges or said slit.

5 longitudinal slit 19. Radiant energy apparatus comprising an electrically conducting tubular member having a along the length" thereof. the "capacity between the edzes of said slit being so related to the inductance of the interior circumterential conducting path-oi said member that said path is resonant at a predetermined Irequency, means for exciting said path at said frequency and utilization apparatus coupled to the edges of said slit.

GEORGE 'LINDLEY USSEIMAN. 

